(howto)从输入到前置摄像头获取面部作为UIImage

Question

我分辨扫描前置摄像头输入的面,检测它们,并让他们作为任务的UIImage -objects.我正在使用AVFoundation来扫描和检测面部.

像这样:

let input = try AVCaptureDeviceInput(device: captureDevice)
captureSession = AVCaptureSession()
captureSession!.addInput(input)

output = AVCaptureMetadataOutput()
captureSession?.addOutput(output)

output.setMetadataObjectsDelegate(self, queue: dispatch_get_main_queue())
output.metadataObjectTypes = [AVMetadataObjectTypeFace]


videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
videoPreviewLayer?.frame = view.layer.bounds
view.layer.addSublayer(videoPreviewLayer!)

captureSession?.startRunning()

在委托方法didOutputMetadataObjects我正在面对AVMetadataFaceObject并用红框高亮它像这样:

let metadataObj = metadataObjects[0] as! AVMetadataFaceObject
let faceObject = videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadataObj)
faceFrame?.frame = faceObject!.bounds

问题是:我如何获得面部作为UIImages？

我试图跳过' didOutputSampleBuffer ',但根本没有调用它:c

Answer 1

- (UIImage *) screenshot {

CGSize size = CGSizeMake(faceFrame.frame.size.width, faceFrame.frame.size.height);

UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen     mainScreen].scale);

CGRect rec = CGRectMake(faceFrame.frame.origin.x, faceFrame.frame.orogin.y, faceFrame.frame.size.width, faceFrame.frame.size.height);
[_viewController.view drawViewHierarchyInRect:rec   afterScreenUpdates:YES];

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}

从上面得到一些提示

  let contextImage: UIImage = <<screenshot>>!
let cropRect: CGRect = CGRectMake(x, y, width, height)
let imageRef: CGImageRef =     CGImageCreateWithImageInRect(contextImage.CGImage, cropRect)
let image: UIImage = UIImage(CGImage: imageRef, scale:   originalImage.scale, orientation: originalImage.imageOrientation)!